/*
 * $AIST_Release: 0.9.0 $
 * Copyright 2011 Information Technology Research Institute, National
 * Institute of Advanced Industrial Science and Technology
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *    http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package hadoop

import scala.collection.JavaConversions._
import org.apache.hadoop.io.BytesWritable
import util.JavaTypes.JIterable
import aggr.Serializer.serialize
import aggr.Deserializer.deserialize

class SCReducer extends SCReducerBase[BytesWritable, BytesWritable] {

  override def reduce(key: BytesWritable, values: JIterable[BytesWritable], context: Context): Unit = {

    nTables match {
      case 0 => 
      case 1 => 
        val k = deserialize(keyType, Utils.copyToByteString(key))
        val data = values.iterator.map { v =>
          (k, deserialize(valType, Utils.copyToByteString(v)))
        }

        aggr.aggregate(data) { (k, v) =>
          context.write(
            new BytesWritable(serialize(aggr.getKeyType().getOrElse(keyType), k).toByteArray),
            new BytesWritable(serialize(aggr.getValueType().getOrElse(valType), v).toByteArray))
        }
      case _ => 
        // When number of tables is two or larger, writes data as it is.
        for (v <- values) {
          context.write(key, v)
        }
    }
  }
}
